This invention relates generally to an electrostatographic printing machine, and more particularly concerns a printing machine arranged to reproduce a plurality of sets of transparencies having an ordered sequence.
An electrostatographic process involves the formation and utilization of electrostatic latent charge patterns for the purpose of recording and reproducing the patterns in viewable form. The field of electrostatographic printing includes electrophotographic and electrographic printing. Electrophotographic printing is that class of electrostatographic printing which employs the photosensitive medium to form, with the aid of electromagnetic radiation, the electrostatic latent charge pattern. Xerography, which employs infrared, visible or ultraviolet radiation and xeroradiography are sub-classes of electrophotography. Electrography is that class of electrostatography which utilizes an insulating medium to form, without the aid of electromagnetic radiation, the electrostatic latent charge pattern. Xero printing, which uses the pattern of insulating material on a conductive medium to form electrostatic charge patterns and electrographic recording, which uses a charge transfer between the plurality of electrodes to form directly electrostatic charge patterns, are sub-classes of electrographic printing. In all of the foregoing machines, it is highly desirable to be capable of reproducing transparencies. More particularly, it is highly advantageous to provide a plurality of transparencies in an ordered sequence with each transparency being reproduced sequentially so as to produce a plurality of sets of collated copies.
The process of electrophotographic printing will be described hereinafter as an examplary system for achieving the foregoing. An electrophotographic printing machine exposes a charged photoconductive member to a light image of a transparency being reproduced. The irradiated areas of the photoconductive surface are discharged to record thereon an electrostatic latent image corresponding to the transparency. A development system moves a developer mix of carrier granules and toner particles into contact with the photoconductive surface. The toner particles are attracted electrostatically from the carrier granules to the latent image forming a toner powder image thereon. Thereafter, the toner powder image is transferred to a sheet of support material. After transferring the toner powder image from the latent image to the sheet of support material, a fusing device permanently affixes the toner powder image thereto. The foregoing briefly the basic operation of an electrophotographic printing machine. This concept was originally disclosed by Carlson in U.S. Pat. No. 2,297,691 and is further amplified and described by many related patents in the art.
Many special purpose electrophotographic printing machines have been developed and are in wide commercial use. For example, electrophotographic printing machines are presently commercially available for reproducing microfilm. Machines of this type are described in U.S. Pat. No. 3,424,525 issued to Towers et al. in 1969; U.S. Pat. No. 3,542,468 issued to Blow, Jr. in 1970; and U.S. Pat. No. 3,547,533 issued to Stokes et al. in 1970. In general, a microfilm reproducing machine produces an enlarged copy of a microfilm original. However, high quality reproduction of color slides has only been recently achieved. This process is exemplified by co-pending application Ser. No. 540,617 filed in 1975, and co-pending application Ser. No. 663,389 filed in 1976. As disclosed in the foregoing applications, a light image of a color transparency is projected onto a mirror. The mirror reflects the light image through a screen and field lens onto the charged portion of the photoconductive surface. This light image is filtered to record a single color electrostatic latent image on the photoconductive surface. Successive single electrostatic latent images are recorded and developed with the appropriately colored toner particles. These toner powder images are transferred to a sheet of support material, in superimposed registration with one another. This multilayered tone powder image is then permanently affixed to the sheet of support material forming a copy of the color slide being reproduced. Improvements in this basic process include positioning a mirror in the path of the transparency light image to direct the light image onto the charged portion of the photoconductive member with the mirror being readily removable from the optical light path so as to reproduce opaque original documents.
It has been found to be highly desirable to place a set of slides in a slide projector, in an ordered sequence, and automatically index these slides to form a plurality of collated sets of copies.
Accordingly, it is a primary object of the present invention to improve electrostatographic printing machines by reproducing sets of collated copies from an ordered arrangement of transparencies.